The present invention relates to reverse flow air cleaner arrangements. That is, the invention concerns air cleaner arrangements wherein filtering flow is in a direction with the xe2x80x9ccleanxe2x80x9d side of the air filter being around an exterior thereof, and the xe2x80x9cdirtyxe2x80x9d side of the air filter being along an interior thereof. The invention particularly concerns such air cleaner arrangements having drainage systems for water accumulating in an interior of associated air filter elements. The invention also concerns provision of preferred components, such as air filter elements, for use with such arrangements; and, to methods involving the use of such arrangements.
In general, air cleaner arrangements include a housing and an air filter element. The housing is configured such that air is directed through the air filter element, for filtering. Various geometric configurations of the air cleaner housing, the air filter element, and related seal arrangements are used to effect this.
Many air cleaner arrangements include generally cylindrical air filter elements. Such elements typically include filter media arranged in a cylindrical pattern, with end caps. Seal arrangements are used either on or in conjunction with the end caps, to provide appropriate sealing with the housing or other portions of the air cleaner, and to control the direction of air flow.
Reverse air flow air cleaner arrangements are generally those in which air is directed to an interior of the air filter element before it is filtered, and the air is filtered as it passes through the air filter element from the interior to the exterior. If the air filter element is cylindrical, this means that the unfiltered air is directed into the interior of the cylinder, and then through the filter media, to an exterior, during filtering. Material entrained in the air directed into the air filter, then, is left along an interior of the cylindrical filter media.
Consider, for example, a reverse flow air cleaner arrangement, having a cylindrical air filter element, utilized on an over the highway truck. Air directed into the interior of the cylindrical element may include dust, leaves, large particulates, and even moisture entrained therein. This material will tend to build up in the interior of the air filter element, in time. If the water depth inside the air filter becomes significant, the water, alone or with fine particulates or salt in suspension, can permeate the filter media. This has the potential to damage engine components. It would be preferred that arrangements be provided to drain the water from the interior of the filter element.
In those arrangements wherein the filter element is operationally oriented such that the longitudinal axis of the cylindrical air filter is substantially vertical, drainage arrangements involving drainage apertures in one of the end caps have been used. In general, these have involved offset (from a central location) apertures in one end cap, and unless the air filter element is oriented nearly perfectly vertically, drainage is inefficient. Also, in such arrangements debris can sometimes collect along interior surfaces of the housing when the arrangement is opened and the element is removed; and, unless the housing is thoroughly cleaned before the element is reinserted into the housing, the debris can interfere with attainment of a good seal at critical locations.
According to the disclosure of U.S. Ser. No. 08/742,244, an air filter arrangement is provided. The air filter arrangement includes a housing and an air filter element having first and second opposite end caps, filter media and an open filter interior. The first end cap has an air inlet opening therein, for air to be passed into the arrangement to be filtered. The second end cap has a central drainage aperture and an interior surface constructed and arranged to funnel moisture that collects on the second end cap interior surface to the central drainage aperture, and outwardly from the filter element. The central drainage aperture is preferably positioned at a center of the second end cap, with a longitudinal axis of the air filter element passing therethrough. The air filter arrangement also includes an air flow direction arrangement constructed and arranged to direct air flow into the housing, into the open filter interior, through the filter media for filtering and then outwardly from the housing, as filtered air. The air flow direction arrangement generally comprises various features of the housing, seals and filter element.
Preferably, the interior surface of the second end cap is circular. In certain embodiments it includes a plurality of radially directed troughs which terminate in the central drainage aperture. The troughs can be used to help funnel and direct moisture collected on an interior surface of the air filter element in use (i.e., xe2x80x9cwhen operationallyxe2x80x9d or xe2x80x9coperativelyxe2x80x9d assembled).
In certain preferred arrangements, according to the U.S. Ser. No. 08/742,244 disclosure, the second end cap includes an outer annular compressible portion and the housing includes an annular sealing surface against which the second end cap outer annular compressible portion is sealed, when the air filter arrangement is operatively assembled for use. Such a seal is referred to herein as a peripheral or annular radial seal, around the second end cap. That is, in this context the term xe2x80x9cannularxe2x80x9d refers to a sealing portion around the outside of the end cap, which seals under radial compression.
In a preferred embodiment, according to the U.S. Ser. No. 08/742,244 disclosure, the housing includes a base having a central, preferably recessed, pan and a sealing bead circumferentially positioned around the central recessed pan. A drainage aperture is provided in the central pan, so that water collected in the pan can be removed from the housing. With such an arrangement, preferably the second end cap is constructed and arranged to form a secondary seal with the sealing bead in the base, when the air filter element is operatively positioned within the housing. Preferably the manner of engagement with the seal bead is by provision of a mating xe2x80x9ctroughxe2x80x9d in the second end cap outer surface.
According to the U.S. Ser. No. 08/742,244 disclosure, preferably the second end cap outer surface has an outer edge or lip; and, the second end cap outer surface is recessed (or depressed) in extension between the outer edge and the trough which engages the sealing bead and the base. In this manner, a preferred gap or space is provided between the filter element second end cap, and the housing base, in the region between the sealing bead of the base and an outer peripheral area of the base. A space in this location accommodates debris that may collect in the housing, without interference with the seal between the second end cap and the housing. This is facilitated by those arrangements involving provision of the seal along an annular portion of the end cap, as a radial seal, rather than as an end or axial seal.
According to the U.S. Ser. No. 08/742,244 disclosure, preferably the second end cap outer surface is configured to provide a funnel surface having a declination angle of at least about 1xc2x0, and preferably 1xc2x0 to 3xc2x0, in the region of extension between the outer edge of the second end cap and the portion of the end cap which engages the seal bead in the base.
In preferred arrangements, according to the U.S. Ser. No. 08/742,244 disclosure, an evacuation valve is mounted in the drainage aperture of the recessed pan in the base. This provides for a preferred, controlled, drainage of moisture from the system.
In preferred embodiments, according to the U.S. Ser. No. 08/742,244 disclosure, a soft polymeric material is utilized for the first and second end caps. Preferably each of the polymeric end caps comprise polyurethane. For the end caps, a polyurethane foam material having an xe2x80x9cas moldedxe2x80x9d density of about 14-22 lbs per ft3 will be preferred (most preferably about 18.4). In some embodiments, the same material can be utilized for both end caps.
In preferred constructions, according to the U.S. Ser. No. 08/742,244 disclosure, an air inlet tube is provided in the housing, which is configured to generate a radial seal with the first end cap of the filter element.
In an alternate embodiment, described in the U.S. Ser. No. 08/742,244 disclosure, an arrangement having a sheet metal end cap as the second end cap is provided. This arrangement is preferably axially sealed, by provision of a primary seal gasket axially compressed between the second end cap and the base, when the air filter arrangement is operationally assembled. A secondary gasket can also be provided in such arrangements between a selected portion of the second end cap and the housing base.
According to the U.S. Ser. No. 08/742,244 disclosure, a preferred filter element is provided. The preferred filter element comprises a generally cylindrical extension of filter media. The filter media may be, for example, a pleated paper filter media. Preferably, an inner support liner and an outer support liner are provided, for the cylindrical extension of filter media. Preferably the arrangement has first and second end caps, the first end cap including an air inlet opening therein. The second end cap preferably has a central drainage aperture and an interior surface constructed and arranged to funnel moisture, collected on the interior surface of the second end cap, to the central drainage aperture. The central drainage aperture is preferably located at an approximate center of the end cap, on a longitudinal axis of the cylindrical extension of filter media. A preferred configuration for the interior surface of the second end cap, is as an interior of a funnel. In some embodiments, the second end cap interior surface includes a plurality of radially directed troughs therein, which terminate at the central drainage aperture.
Other preferred features for the preferred air filter element described in the U.S. Ser. No. 08/742,244 disclosure include: a circular sealing trough on an outer surface of the second end cap; and, a recess between an outer edge of the end cap outer surface and the circular trough. Also, a compressible region providing for a radial seal along an annular portion of the second end cap is preferred.
According to the U.S. Ser. No. 08/742,244 disclosure, a method of operating a reverse flow air filter arrangement is provided. In general, the method comprises collecting moisture within the filter element and draining the moisture from the filter element through a central aperture in the end cap, by funneling the moisture to the central aperture.
According to the portion of the present specification which comprises added disclosure relating to FIGS. 9-14, the end cap which includes the drainage aperture therein, is provided in a preferred composite structure. The composite results from an outer portion comprising a soft, compressible, polymeric material; and, an inner xe2x80x9cpre-formxe2x80x9d or insert, which becomes positioned between the polymeric material and the inner liner, during molding. The insert has preferred inner surface characteristics, to accomplish desirable flow of liquid to the drainage aperture, and outwardly from an interior of the filter element. In addition, it has preferred features to facilitate molding using a free rise technique.
The preferred xe2x80x9cpre-formxe2x80x9d or insert also has depending legs with outwardly projecting feet. The legs and feet operate, cooperatively, as a mold stand-off for media. An underside of each foot has a bead thereon, to facilitate this.
Further features and advantages from the preferred inserts and xe2x80x9cpre-formsxe2x80x9d described herein, as well as techniques for use, will be apparent from the more detailed description below.